The National Highway Traffic Safety Administration is requiring a phase in of tire pressure monitoring systems in vehicles. Various types of pressure sensing systems for monitoring the pressure within the tires of an automotive vehicle have been proposed. Such systems generate a pressure signal using an electromagnetic (EM) signal which is transmitted to a receiver. The pressure signal corresponds to the pressure within the tire. When the tire pressure drops below a predetermined pressure, an indicator is used to signal the vehicle operator of the low pressure. Many vehicles require different tire pressures in the front of the vehicle and the rear of the vehicle. Therefore, it is important to know the relative position of the pressure sensor and thus the tires relative to the vehicle.
Proposed tire pressure monitoring systems use RF signals between a receiver and the pressure sensors. RF reception between the tire pressure monitoring sensors in each wheel and the tire pressure monitoring receiver is not always sufficient. RF reception between the tire pressure monitoring sensors and the receiver is not fully predictable during the design process of the vehicle. Robust designs require extensive in-vehicle testing of representative vehicles to establish the receiver location within or outside of the vehicle. Various impediments to the RF signals include the sheet metal, wiring variations, powertrain, and wheel configurations. Such designs are typically not available until late in the product development cycle. Using a conventional receiver located within or outside the vehicle and the various pressure monitoring systems may therefore be inhibited.
It would therefore be desirable to provide a system that prevents attenuation of the RF pressure sensor signal so that reliable pressure monitoring may be performed.